Here is a timeline of school shootings worldwide, which begins on February 2, 1996. After a decade of these assaults and similar rampages, is there any consensus on what marks the profile of the non-political killers? “We are reaching that stage of desensitization at which the infliction of pain and suffering has become a source of entertainment: vicarious pleasure rather than revulsion,” West Point Professor David Grossman wrote in his 1996 book On Killing. “We are learning to kill, and we are learning to like it.”

The execution of Amish little girls is another basement of horror. What has poisoned the minds of these people so deeply as to set off such awful scenes?